x86汇编语言之大小写快速转换

A  41H  0100 0001B
B  42H  0100 0010B
C  43H  0100 0011B
D  44H  0100 0100B

a  61H  0110 0001B
b  62H  0110 0010B
c  63H  0110 0011B
d  64H  0110 0100B

or 0010 0000B ;大写变成小写, 小写依然还是小写

and 1101 1111B ;小写变成大写, 大写依然还是大写

assume cs:code ,ds:data

data segment
	db 'ABcDEF'
	db 'abCdef'
data ends


code segment

	start:
		mov ax ,data
		mov ds,ax
		mov bx,0
		
		mov ax,data
		mov es,ax
		
		mov cx,6
		
downLetter:		;大写转小写
		mov dl,ds:[bx]
		or dl,00100000B
		mov es:[bx],dl
		inc bx
		loop downLetter
		
	
		mov cx,6
		mov bx,6
upLetter:		;小写转大写
		mov dl,ds:[bx]
		and dl,11011111B
		mov es:[bx],dl
		inc bx
		loop upLetter
		
		mov ah,4ch
		int 21h
		
	
code ends
end start

assume cs:code ,ds:data

data segment
	db 'ABcDEF'
	db 'abCdef'
data ends


code segment

	start:
		mov ax ,data
		mov ds,ax
		mov bx,0
		
		mov ax,data
		mov es,ax
		
		mov cx,6
		
changeLetter:		
		;大写转小写
		mov dl,ds:[bx]
		or dl,00100000B
		mov es:[bx],dl
		;小写转大写
		mov dl,ds:[bx+6]
		and dl,11011111B
		mov es:[bx+6],dl
		inc bx
		loop changeLetter
		
	
		mov ah,4ch
		int 21h
		
	
code ends
end start